# 


Circular  No    60 

I  mini  States  Department  of  Ajjri* 

r—~  BUREAU    (>!•     BNTOMOLOOV 

I      i>    HOWARD    I  in 


mi    imtoim  t  it  i  uum.i    u 
/'■■iiiin  rn/,,  Linn,  i 

B  J      I  II.     t  '  I  I  I  I   I  I    N  I  >  I    S  . 

/./.  i  (ling  l 

i  i;  \i.  I'M  \i;  m   i  i  BIS  i  [I  3. 

The  worst   of  the  raanj   destructive  enemiee  ol   cabbage   und   othei 
crucifera  is  the  larva  or  caterpillar  of  a  white  butterfly  km >w  n  to  science 

r  ni in  i  Pit  lis)  rii pit 
Linn.  The  caterpillar, 
called  the  imported  cab- 
bage worm,  ie  altogether 
too  well  known  by  farm- 
en  throughout  this  coun- 
try ae  well  as  in  the  <  >1«  1 
World,  and  the  adult  in 
Beet,  the  imported  cab- 
bage butterfly,  called  also 
the  white  <>r  rape  butter- 
fly, is  o  familiar  objeel  to 
nearly  everyone.  It  is 
generally  recognized  that 
the  butterfly  ie  the  pan  ni 
of  the  "  worn 

This  cabbage  worm  ie 
velvety    green    in    color, 
much   like  the   cabb 
mi  which    it   feeds ;  and 
the  -  of  the  body, 

if  viewed  through  an  or- 
dinary hand  lens,  is  Been  to  be  somewhal  rough  and  finely  dotted  with 
small  black  Boots.  There  is  a  faint  yellow  Btripedown  the  middle  of  the 
back  and  a  i'mu  of  yellow  spots  along  each  side  in  line  with  the  Bpiracles 
or  breathing  pores.  It  measures,  when  full-grown,  about  an  inch  and  a 
fourth,  presenting  the  appearance  Bhown  in  figure  1,  c. 

The  butterfly  has  a  win.  rly  two  inches,  and  i-  white, 

marked  with  Mack  near  the  tips  ol  the  fore-wings,  a-  Bhown  at  figure 
I.  a.  representing  the  female.  In  tin-  Bex  there  are  two  conspicuous 
black  Boots  <>n  each  fore-wing;  the  malt  has  only  one.     Both 


Tib    i  -  /■■  female  butterfly:  '.   abovi 

Ian  .i  in 
iiiitiinii  position  ■•II  i  i  led  cbrj  - 

'  -iiu'iiii v  enlarged    /.,  mon 


sexes  have  a  corresponding  smaller  black  ^ i >< >t  at  the  upper  extremity  oi 
the  hind-wings.  The  body  of  the  Female  is  whitish  ;  thai  of  the  male 
is  usually  darker  above.  The  male  is  generally  a  little  the  smaller. 
The  under  surface  of  the  hind-wingS  are  uniform  Satiny  straw-yellow  and 

there  are  generally  two  black  spots  showing  through,  in  both  sexes. 

'Flu-  eggs  are  fusiform,  pale  yellowish,  and  strongly  ribbed  (fig.  I.  &). 
They  are  large  enough  to  be  readily  seen  with  the  unaided  eye,  and  are 
deposited  singly,  usually  on  the  lower  surface  of  the  outer  leaves  of  cab- 
bage and  other  food  plants. 

When  the  caterpillar  or  "worm"  becomes  full  grown  it  attaches  itself 
to  a  cabbage  leaf  or  other  nearby  object,  fastens  itself  by  means  of  a 
stiingdike  girdle,  and  often  within  the  same  day  transforms  to  a  chrysa- 


p-'/xi 


\         / 


P-T 


\ 


i. 


^ 


Pia.  2.— Imported  cabbage  butterflj      male,  wings  expanded,  :it  left;   wings 
folded  in  nut  urn  I  resting  position  at  right— somewhat  enlarged  [original). 

lis  of  the  appearance  indicated  at  figure  1.  d.  The  chrysalis  is  of  varia- 
ble color,  seeming  to  be  influenced  in  this  respect  by  the  object  upon 
which  it  is  placed.  The  color  thus  varies  from  dirty  gray  to  yellow, 
green,  and  dark  gray.  The  length  of  the  chrysalis  is  a  little  less  than 
three-fourths  of  an  inch. 

NATURE   OP   INJURY. 

This  cabbage  worm  has  been  rightly  termed  the  bane  of  the  cabbage- 
grower,  and  the  dread  of  every  careful  cook  and  housewife.  It  begins 
work  early  in  the  season,  and  the  principal  damage  i^  therefore  usually 
to  young  plants.  After  riddling  the  outer  leaves,  which  continue  after- 
ward attached  to  the  stalk,  it  attacks  the  more  tender  inner  leaves  as 
they  form,  frequently  secreting  itself  in  the  head-,  which  are  made  most 
unsightly  by  its  dark  green  excrement,  and  where  it  is  difficult  to  reach 
with  insecticides.  As  a  result,  cabbages  before  being  sent  to  market 
must  lie  carefully  examined  and  the  damaged  leaves  plucked  away ;  and 
before  cooking  it  is  frequently  necessary  to  tear  the  heads  apart  to  see  that 
no  disgusting  "worm"  is  lurking  within.  Even  after  the  dish  is  cooked 
there  is  danger  of  an  admixture  of  animal  with  the  vegetable  food.  In 
cool  weather  the  caterpillar  frequently  feeds  in  free  exposure  on  the 
upper  surface  of  the  leaves  in  the  sunshine. 


8 


\_  , .,,  j    £  1869,  when  thia  i  abbage  worm  »  d  to  limit*  'I 

areas  in  Canada,   New   England,  and   New  York,  ii  did  greal  dan 
At  Si.  Albans  Bay,  Vt.,  in  thai   yeai   it  caused  the  total  destruction  ol 

p  ,,f  3,000  cabbage  plants      The  worms  made  theii   appearance 
.it. cut  the  first  ol  September,  and  there  were  from   I"  to  50  on  a  head. 

TheAbbi  Provancher  estimated  th<  same  year  a  1<  &240.0 n  the 

vicinity  of  Quebec  alone.     One  farmer  near  Montreal  losl   in  a  single 

n  over  12,000  heads  of  cabbage.     The  following  year,  accordii 
Mi     Vngus,  the  entire  crop  of  cabbage  and  cauliflower  in  Borne  places 
about   New   York  City,  where  the  insects  had  appeared  onlj  the  yeai 
before,  was  destroyed.     The  loss  was  estimated  at  half  a  million  dollars 

\n  interesting  feature  connei  ted  with  the  establishment  of  this  in 
in  America  is  the  practical  extirpation,  at  !  illetl 

southern  cabbage  butterflj  {Pontia  protodici   Boisd.1)  in  many  regions. 
This  is  accounted  for  in  pari   hj    thi  earlier  ppearance  of  the 

imported  Bpecies,  enabling  the  caterpillars  to  obtain  possession  of  the 

fee< ling  plan-  and  crowd  <>ut  ill"  less  hardy  native   form.2 

ORIGIN     VND    DIS  I'Klia    in  >N. 

imported  cabbage  butterflj    was   introdi I  from    Europi 

nape  half  a  centurj   before  the  dat(  nl  writing,3  and  was  first 

■  I   from  a  capture  at  Quebec,  Canada,  in    I860.     It   was  nol 

.  en   until   two  years   latei .  in  the    ■  . locality.     I  • 

-  after  this  it  was  observed  at  intervals  in  other  portions  ol  '  'anada. 
In  1865  it<  firsl  appearance  in  the  United  States  was  noticed  in  Maim 
i'li.    following  year  it  was  seen  in  north  Hampshire  and  Ver- 

mont.    Bj   1868  it  had  reached  New  York,  and  a  Few  years  latei  b 

;  attention,  as  each  year  thereaftei  it  was  found  in  Borne  new 
locality.  In  1875  it  appeared  in  Cleveland,  Ohio,  and  two  years  later 
m  Illinois.  By  1S^>  it  had  penetrated  southward  to  the  Gulf  region. 
This  distribution  has  continued  until  now  the  spi  known  prac 

ti,.i||\   in  evi  and  Territory  of  the  Union,  although  ii   is  occa 

•  ,llv  , ,  | mii  i,  .1  as  new  to  some  mi  ire  or  l<  sa  isolated  locality. 
It  does  not  appear  t . .  be  an  inhabit  in!  of  any  particular  life 
-. .  nun ;  to  be  as  mm  Ii  ol  in  the  <  lull 

I  ngland. 
I„  the  l  II'  misphere  this  butterfly  rangt  -  from  the  Atlant 


-  native  Bpeciee  and  the  imported  butterflj  erallj 

rred  to  in  literature  as  Pieris  protodict  and  res| lively. 

Ii  i-  well  known  thai  neat  introduced  from  tl  H 

hardy  than  nativi  ind  survivet litione  which 

would   be  unfavorable  i"  the  latter.     In  the  writer's  experience,  the  southern 
cabbage  but terfl)  is  more  susceptible  to  disease  than  the  imported  specii 
sionalh  the  latter  returns  in  moderate  numbers  to  localities  from  which  it  has 
apparent  1>  been  absent  i"<  !<.n^  periods. 

was  introduced  in   1856  ■•<    1857    see  Rept.  Dept.    ^gr.  for 

lixs        \  iojji  iphi  ■   ..-•-■  -iitit  "i"  tln>  Bpecies  is  ui\>-n  l.\  Scuddei     B   I 

terfl  n  I  .  S.  and  Can..  Vol.  II.  pp.  1171    1190,  1205   1218  . 


the  Pacific,  in  most  localities  between  the  thirtieth  and  sixtieth  degrees 
of  latitude.  In  Switzerland  it  occurs  on  the  level  of  perpetual  snow, 
and  in  this  country  it  lias  been  taken  on  the  barren  subalpine  heights 
of  the  White  Mountains. 

FOOD    AND   OTHER    HABITS. 

The  imported  cabbage  worm  feeds  on  the  foliage  of  nearly  all  cru- 
ciferous plants,  is  particularly  fond  of  cabbage  and  cauliflower,  and 
somewhat  less  destructive  to  turnip,  radish,  mustard,  and  horseradish. 
It  also  does  considerable  injury  to  ornamental  plants,  such  as  nastur- 
tium, mignonette,  sweet  alyssum,  and  spider  plant  (Cleome).1 

The  butterflies  sip  \\ni  nectar  of  (lowers  of  many  kinds,  and  are  to  lie 
seen  any  time  hovering  oVer  them.  They  are  especially  fond  of  the 
white  blossoms  of  crucifers.  also  of  such  plants  as  white  aster,  lavender, 
and  thistle.  Like  other  butterflies,  this  species  is  diurnal,  and  is  on  the 
wing  from  early  morning  until  near  dusk.  It  is  a  comparatively  slow 
flyer,  hut  capable  of  extended  flight  for  long  distances.  The  butterflies 
sometimes  congregate  in  immense  swarms,  as  has  frequently  occurred 
where  the  insect  has  emigrated  from  the  continent  of  Europe  to  England. 
Its  occurrence  in  mid-ocean  has  been  recorded. 

LIFE    HISTORY. 

The  butterflies  appear  as  early  as  March,  even  in  the  Northern  States. 
and  thereafter  can  usually  be  seen  flying  about  cabbage  fields  and  else- 
where, throughout  the  year,  until  after  several  severe  frosts  in  October. 
In  the  Gulf  States  they  occur  throughout  the  season. 

Egg  deposit  commences  soon  after  the  butterflies  appear;  in  fact. 
pairing  and  egg-laying  may  begin  within  a  day  or  two  after  the  adult 
issues  from  the  chrysalis.  The  duration  of  the  different  stages  varies 
according  to  temperature.  The  observed  egg  period  is  from  four  to 
eight  days. 

The  larva  eats  voraciously  and  grows  with  great  rapidity,  attaining 
full  maturity  in  from  ten  days  to  two  week  after  hatching.  It  molts 
four  times;  hence  there  are  five  distinct  stages,  the  first  molt  taking 
place  (in  warm  weather)  in  about  two  days  from  the  hour  of  hatching, 
the  second  stage  lasting  two  or  three  days;  the  third  and  fourth,  one  or 
two  days  each,  and  the  fifth,  four  or  five  days'-'.  The  duration  of  the 
chrysalis  stage  is  from  seven  days  to  a  foil  night  during  the  summer 
time,  but  the  last  chrysalides  formed  in  the  more  northern  States  remain 
undeveloped  during  the  winter  until  the  following  spring. 

The  life  cycle  occupies  periods  varying  between  twenty-two  days 
and  five  weeks.  Even  in  New  England  this  species  is  credited  with 
being  triple-brooded,  but  in  the  District  of  Columbia  and  vicinity  there 

Ii  is  a  decided   pest  mi  iliis  plant   in  the  District  of  Columbia. 

Technical  descriptions  of  the  different  larval  stages  witli  particular  reference 
t<>  wing  development  are  given  by  W.  F.  Mercer  (Jour.  X.  Y.  Em.  Boc.,  Vol. 
VIII,  pp.  L-20,  March,  L900). 


,„„-.  be  one  or  more  addition  »ne,  and  then    it  b  i ibility 

,,l:l,  least  Bii  in  the  extreme  Booth.    The  fii  ition  develoi 

it ilil  plants. 

\  \ri  R  \i.    ENEMIE8. 

w,,,.  ,,  not  for  certain  natural  checks  this  would   be  b  still 

peater  pest  than  it   is.     The  b1  important  oi  its  inBecl  enemi< 

Bmall  parasites,  all  introductions  from   Europe.     One  ol  them,  a   Bi 


-«f~ 


lUk'llh    TIKI. 

conid,  Apanteles  glomeratus  Linn.  (fig.  3),  was  purposely  imported  in 
from  England.     During  the  autumn  of  1904  this  Bpecies  held  its 


t 


IV 


:  I 

under  complete  control  at  Washington,  D.  C,  killing  every   '  worm  " 
which  came  under  the  writer's  observation.     A  larva  which 
destroyed   by  this    parasite  is  Bhown  in   figure    I.    together    with    thi 
parasite's  cocoons.     A  secondary  parasite,  a  minute  chalcis  fly,  Tetras- 
tichus    microgastri    Bouche,   was  also    present,  but    did    not    militate 
against  the  effectiveness  oi  the  Apanteles.     Of  Bimilar  importance  to 


6 


this  Apantelea  is  a  chalcis  fly.  Pteromalus  puparum  Linn.  (fig.  5), 
noticed  in  this  country  in  1869,  having  evidently  been  imported  with 
its  host. 

Wasps,  particularly  Polistes  pallipes  Lepeh,  and  related  forms  are 
also  of  great  service  in  reducing  the  numbers  of  this  and  other  cabbage 
worms,  appearing  to  prefer  them  to  other  prey. 

A  small,  evil-smelling  plant-bug,  Phymata  wolffii  Stal.  (fig.  6), 
secretes  itself  in  flowers,  such  as  thistle  and  goldenrod,  and  destroys 
numbers  of  the  butterflies,  capturing  them  and  sucking  out  their  vital 
fluids. 


Fig  5     Pttrnmal  female  at  left ;  male  at  right     bigbly  magnified  (original). 

Numerous  other  enemies  attack  this  Cabbage  worm  in  addition  to  tin- 
ones  that  have  been  enumerated,1  and  it  is  sometimes  subjeel  to  a  con- 
tagious bacterial  disease'-'  similar 
to  that  of  the  cabbage  looper.3  It 
is.  however,  less  susceptible  to  this 
malady,  and  is  seldom  destroyed  in 
any  numbers  by  it.  The  parasitic 
flies  can  he  encouraged  by  collect- 
ing the  larva'  and  chrysalides  of 
,,,  ,      ,  ,  ,„.    the  cabbage  butterfly  and  placing 

!  m.   I.      Vhymata  wolffu     a,  dorsal  view  .  '>.  lat-  >-  ■  ' 

eral  view ;  c,  f t  leg :  d,  snout— a,  b,  enlarged      them    in    barrels  or   lioxes   covered 

,    d  more  enlai  ged  •  from  Rilej  '  •.  1 

with     coarse     mosquito     netting, 

which  will  prevent  the  butterflies  from  escaping  when  they  develop 
and  permit  the  much  smaller  parasites  to  issue  ami  continue  their  good 
woi  k. 

REMEDIES. 

In  the  treatment  of  this  species  it  should  be  kept  in  mind  that  other 
"  worms"  and  other  cabbage  pests,  are  more  often  present  than  not. 

Arsenicals. — The  best  remedy  i<  one  of  the  arsenicals;  and  Paris 
green  and  arsenate  of  lead  are  prefei  red  to  others  in  common  use.  If  the 
former  is  u^a\  it  may  be  applied  either  dry  or  wet.  preferably,  however. 


1  Among  ether  predaceous  enemies  observed  in  tins  country  are  the  wheel  bug 
[Arilus  cristatus  Linn.)  and  the  armed  soldier  bug  {Podisus  spinosus  Dall.). 
Che  cabbage  worm  is  also  parasitized  by  the  Tachina  fly  Exorista  vulgaris  Fall, 
'the  writer  has  a  list  of  in  additional  European  parasites. 

Micrococcus  pieridis  Burrill.     3Autographa  [Plusia)  >>*    a        Riley. 


I  the  rate  ol  about  I  pound  "I  the  poison  to  160  gal  lot 
«  iter,     It  Bhould  !"■  applied  when  the  plants  are  iii-i  Bel  oul 
insure  the  poison  reaching  the  young  larva   before  thej  have  burrowed 
far    iui"   the   heads.     Other  applications    Bhould    follow    ac    required 
These  can  be  made  with  absolute  aafet)  until  the  heads  are  aboul  hall 

formed,  and,  for  thai  matter,  even  later,  .1-  the  pois lisappears  from 

plants  almost  completely  within  three  "i   four  we<  ks  after  application.' 

Bran  mash.— A  mixture  of  bran  with  Pai  1  ol  the  standard 

remedies  for  cutworms  as  well  ithetesti 

mony  of  some  who  have  used  n  til  against    'cabbage  won 

and  Bhould  !><■  tried  against  the  present  species.      \n-  .1  can  be 

employed  in  the  preparation  ol  this  mixture.  It  is  best  to  mix  the 
bran  with  water  and  BUgar  before  adding  the  poison.  The  proportions 
are  2  or  ■">  ounces  ol  bu  ■  ir  >u  other  sweetening,  and  ibout  I  pound  of 
bran,  d>  a  gallon  of  wati  1  .  0  as  to  make,  wh<  n  stirred,  a  mixture  that 
will  easily  run  through  the  fingers.  In  it-  application  it  1-  merelj 
Bprinkled,  either  wet  or  dry,  over  the  affected  plants. 

I  In  hot-water  remedy.—  As  long  igo  1-  lvv ■".  water,  at  a  tempei  iture 
of  aboul  130  !•'..  was  advised  :i-  ;i  remedy  foi  this  cabbage  "worm." 
It  clues  practically  no  harm  to  the  plants  and  kills  all  insects  with  which 
it  comes  in  contact.     It   i  ly  applicable  t"  large  fields,  bowev<  r, 

on  accounl  of  the  difficult)  of  maintaining  the  proper  temperature. 

Kerosem  emulsion  is  nol  as  effective  as  tin'  arsenicals,  because  in  its 
application  it  is  necessary  for  the  epra)  tocomi  into  direct  contact  with 
the  larva5  in  order  to  kill  them. 

Pyre  thrum  is  not  bo  useful  ;i-  an  arsenical.     <  »t   it-  effectiveness  I  h 
James  Fletcher,  who  still  advocates  it-  use  in  Canada,  wrote  in    lv,,l 
that  "diluted  with  four  times  its  weight  "I  common  Hour,  and  then  kept 
tightly  closed  for  twentj  tour  hours  (before  use),  leaves  nothing  to  be 
desired,  and  thousands  of  dollars  are  yi  ><l  to  small  growers,  who 

most  need  assistance."  Pyrethrum  is  rather  costl)  and,  though  .— ; •  i *  1  t<> 
discolor  the  leaves,  has  the  advantage  of  not  being  poisonous  to  human 


//•'/  properly  appl  1       tnical  analysis   has 

ahown  that  cabbage  which  has  1  irsenical  in  the 

wa)   prescribed,  and   then  prepared  foi  cooking   in    the  usual  manner  .1  (reek 

late  1 .  has  nol  even  :i  trai 1  arsenic  remaining,     rhe  use  ol  .11  -  jainsl 

cabbage  worms  is  almost  universal  in  the  United  States,  although  growei 
Bometimes  loatb  i"  acknowledge  the  fact   i"i   feai  ol  the  loss  ol  customers  who 
are  do!  full)  acquainted  with  the  harmlessness  ol   the  remedy,     rhere  an    no 
authentic  recorded  instances  known  to  the  writei   ol    ,  from  thi 

sumption  of  cabbage  treated  with  an  arsenical.     According  to  Gillette,  28 
bage  heads,  dusted  in  the  ordinary  way,  would  have  1  □  by  a  human 

being  :u  one  meal  in  ordei   to  produce  poisonous  effects.     Still  il 
In  order  t"  avoid  all  danger,  to  use  othei   insei  ticides  in  the  case  ol  vegetables 
thai  .in-  i"  be  eaten  Boon.     On  tlii-  head  i|  mjgul  be  well  i"  cite  the  expi  1 
of  a  Virginia  market  gardenei   who  d listed  his  cabbages  with  Parif   green  and 
flour,  omitting  to  inform   his  family  ol  the  fact.      \  dai   "i   two  latei   hi 

lily  ni  this  cabbage,  .1-  did  osiers.,  aid  afterwards  was  questioned  by  lii> 
wife  in  regard  to  the  peculiar  powder)  substance  on  the  heads.     Alii. 
oning  was  anticipated,  do  ill  results  followed. 


beings  or  domestic  animals.  If  it  is  not  used  in  liberal  quantity,  how- 
ever, a  proportion  of  the  caterpillars  are  merely  numbed  by  this  mixture 
and  recover.     Younger  caterpillars  are  more  susceptible. 

Hand-picking. — For  the  kitchen  garden  where,  for  obvious  reasons,  it 
is  undesirable  to  use  arsenicals,  hand-picking  is  sometimes  practiced, 
especially  when  plants  are  first  set  out. 

The  corn-meal  remedy. — According  to  Prof.  L.  Bruner,  corn  meal 
dusted  on  cabbage  causes  the  "worms"  to  drop  off.  and  protects  the 
crop  until  the  meal  is  washed  away  by  rain.  It  is  applied  in  the  morn- 
ing while  the  dew  is  on  and  is  said  to  act  as  a  deterrent. 

Chun  farming  and  trap  crops.  —  If  cooperation  in  clean  methods  of 
farming  and  in  the  use  of  arsenicals  could  by  any  possibility  be  secured, 
much  of  the  loss  due  to  the  ravages  of  this  pest  might  be  averted.  The 
practice  of  leaving  cabbage  stalks  in  the  field  after  the  main  crop  i~  <A'\ 
is  a  reprehensible  one.  All  remnants  should  be  gathered  and  de^-troyed 
with  the  exception  of  a  few  left  at  regular  intervals  through  a  field  as 
lures  for  the  females  to  deposit  their  eggs.  Such  stalks,  being  UBi 
should,  where  feasible,  be  freely  poisoned  with  arsenicals  so  that  the 
last  generation  will  have  no  place  to  develop  in  the  fields. 

Tlir  utilization  of  natural  enemies. — It  is  matter  of  common  obser- 
vation, frequently  recorded,  that  the  two  parasitic  enemies  of  this 
species  {Pteromalus  puparum  and  Apanteles  glomeratus)  do  excellent 
service  in  reducing  the  numbers  of  their  host.  The  means  by  which 
they  can  he  encouraged  is  described  on  page  *'.. 

Attempts  have  also  been  made  to  utilize  diseases  of  this  insect  lor  i t > 
control,  but  without  very  encouraging  results. 

Hellebore  will  kill  this  "  worm."'  but  is  not  as  satisfactory  a  remedy 
as  the  arsenicals. 

Trap  leaves.— A  remedy  suggested  by  one  of  our  correspondents  was 
tested  by  the  writer  against  this  and  other  cabbage  "worms,"  includ- 
ing the  looper.  and  found  worthless.  It  consists  in  placing  fresh  cab- 
bage leaves  over  the  heads  at  night,  the  supposition  being  that  the 
"worms"  will  gather  under  these  traps  and  can  be  destroyed  next 
morning. 

Approved : 

James  Wilson, 

Secretary  of  Agriculture. 

Washington,  D.  C,  April  28,  1905. 

O 


DOCUMENT 


UNIVERSITY  OF  FLORIDA 


3    1262    05252    3247 


